OtoNexus is developing the world?s first medical device to provide definitive, objective diagnostic data for the rapid and accurate diagnose middle ear infections, called Otitis Media, in children and adults. This FAST TRACK proposal addresses the clinical difficulty of determining the nature of fluid behind the tympanic membrane (ear drum) in acute infection of the middle ear (Acute Otitis Media - AOM). Clinical studies show that error rates (false negative, false positive) among young physicians average 50%. Accurate detection of AOM depends on detecting and characterizing middle ear fluid. Experienced examiners realize they err in at least 20% of cases even when pneumatic otoscopy is used. Medical practitioners diagnose 17.6M cases of Otitis Media each year at a cost of more than $5 billion in the US. Current diagnostic methods are decades old, highly subjective, and extremely ineffective. Consequently, Otitis Media is both the #1 indication for antibiotic prescriptions in children and the #1 cause for surgery for children. Each year, 667,000 children under 15 receive tympanostomy tubes, accounting for more than 20% of all ambulatory surgery in this group. Excessive antibiotic treatment from over-diagnosis of OM can lead to antibiotic resistance, significant side effects, and increased drug costs. Under-diagnosis can allow the infection to progress, potentially requiring surgery or risking permanent hearing loss. We propose to use Doppler Ultrasound (DUS) to judge the oscillation of the tympanic membrane (TM) after perturbing the membrane position. Membrane mobility is reduced with increasing fluid viscosity. DUS permits a fast and systematic evaluation of this mobility. The proposed device can be used by physician and assistant alike. DUS data can readily affirm the presence of middle ear effusion and estimate its nature. The present project is the basic step to determine the most efficient parameters for assessing TM mobility and therefore the presence and character of middle ear effusion (Phase I), and then integrate the device into a hand-held form factor suitable for testing and commercialization (Phase II). Model TM motions will be observed by DUS with a novel transducer to assess contents of the phantom middle ear, and guide the development of signal processing to distinguish membrane mobility. The device is expected to increase prognostic accuracy, largely eliminate diagnostic uncertainty and resultant over-prescription of antibiotics, reduce unnecessary specialist referrals, reduce instances of hearing loss damage, and place the tools for accurate diagnosis of OM into the hands of the very first clinician the child sees.